1. Field of the Invention
The present invention relates to a computer network, and more particularly to a network device management device on which network management software is running to manage a network device such as a printer (printing device), a copying machine, a scanner, and a multi-purpose device, connected to a network. The present invention also relates to a method and a program for managing such a network device.
2. Description of the Related Art
In recent years, local area networks (LANs) have been more and more widely used to connect computers to one another. A local area network is built over an entire floor or an entire building, or across a plurality of buildings, and thus involves either a small or a large area. A large number of local area networks are built at various locations, and some of them are connected to a worldwide network. In respective LANs connected to one another, various different techniques are used to connect hardware devices to one another, and various network protocols are used.
In the case of a small isolated LAN system, the user of that LAN system can manage his/her own devices. That is, the user can replace a device, install software, and diagnose any problems.
However, in the case of a large scale LAN system or a group of LAN systems connected to one another, systematic “management” is needed. In general, the term “management” is used to describe both management performed by a human network administrator and management performed by software under the control of the human administrator. In describing the present invention herein, the term “management” may encompass “management” over an entire system performed by software, and the term “user” is to describe a human user who uses network management software, can acquire management data via a network using network management software, and can modify the management data. The “user” is usually a system administrator.
Large scale network systems are usually dynamic systems in which it is needed frequently to perform extension and removal of devices, updating of software, and detection of problems. Various large scale network systems provided by various manufacturers are used by various users in various manners. Efforts are being made by various organizations to establish standards of techniques of managing network devices connected to one another via networks in large scale network systems. The International Organization for Standardization (ISO) has proposed a general-purpose reference framework called the Open System Interconnection (OSI) model. The network management protocol according to the OSI model is called the Common Management Information Protocol (CMIP). This protocol is employed in Europe as a common network management protocol.
In recent years, a more versatile network management protocol called the Simple Network Management Protocol (SNMP) has been proposed. This protocol is a modification of CMIP (explanation thereof may be found, for example, in “An Introduction to Management of TCP/IP-Based Internets” (Marshall T. Rose, Prentice Hall; a Japanese version translated by Takeshi Nishida is also available).
A network management system according to this SNMP network management technique includes at least one network management station (NMS), nodes which are managed by the network management station and each of which includes an agent, and a network management protocol used to transmit management information between the management station and the agents. A user can acquire network management data and modify it by communicating with agent software at managed nodes using network management software on the NMS.
Herein, the term “agent” refers to software which is executed as a background process at the respective managed nodes. When the user requests a managed node on the network to transmit management data, the network management software transmits the request, including an object identifier (which will be described later) in a management packet or frame, to the agent at that managed node.
The agent analyzes the received object identifier and reads data corresponding to the object identifier. The obtained data is returned in the form of packets to the network management software. In the above operation, the agent may call a process to read the data.
The agents store management data associated with the respective nodes in the form of databases. Such a database is called an MIB (Management Information Base). FIG. 4 is a conceptual representation illustrating the structure of an MIB. As shown in FIG. 4, the MIB stores data in the tree structure in which identifiers are uniquely assigned to all respective nodes. In FIG. 4, the identifiers of the respective nodes are defined by numerals represented within parentheses. For example, in FIG. 4, node 401 has an identifier 1, and node 402 which is a child of node 401 has an identifier 1.3. Similarly, node 403 has an identifier 1.3.6.1.2. These identifiers of the nodes are called object identifiers. Note that FIG. 4 shows a part of the entire MIB defined in the standard.
The MIB structure described above is called the Structure of Management Information (SMI) and is defined in RFC-115 as the Structure and Identification of Management Information for TCP/IP-based Internets.
A method of implementing an agent is to install an agent on a network board serving as an interface between a printer and a network. This method allows the printer to be managed by the network management software. This makes it possible for the user to acquire information about the printer under the management and modify its status using the network management software. More specifically, it is possible, e.g., to acquire a character string displayed on a liquid crystal display of the printer and to change the default paper cassette.
In the conventional technique, network management software for managing network devices at nodes to be managed is executed on a PC. However, rapid advances in the WWW technology have made it possible to execute network management software on a WWW server (WWW server 118, for example) such that a plurality of PCs can access the network management software via an interface called CGI (Common Gateway Interface). A program for realizing a WWW site is stored on a hard disk (HD) and the program is always executed by a CPU on the WWW server.
Referring to FIG. 11, the operation of a common type of WWW system and the operation of network device management program executed in the WWW system are briefly described below. In FIG. 11, a PC 901 corresponds to the WWW server 118. A WWW server program 911 is running on the PC 901. A large number of WWW page data described in HTML are stored on a disk of the PC 901. WWW browser programs 913 and 914 are running on PCs 903 and 904. When a particular WWW page is requested to be displayed by a user, the WWW browser program 913 or 914 transmits a request for the specified WWW page to the WWW server program 911 running on the PC 901. (PCs 901 and 904 correspond to PCs 103, 104, 111, or 112 shown in FIG. 1.)
In response to the request for the WWW page data from the WWW browser program 913 or 914, the WWW server program 911 transmits the specified WWW page data. The WWW browser program 913 or 914 analyzes the received WWW page data and displays the content of the page according to the description in the data.
In a case where the request for the WWW page data received from the WWW browser program 913 or 914 includes a request via the CGI (Common Gateway Interface), the WWW server program 911 executes an external script or an external program according to a predetermined CGI method and returns WWW page data produced by the external script or the external program to the WWW browser program 913 or 914.
The operation is described in further detail below for the case where network device management program is executed as the external program by the CGI in the above process. When the network device management program 921 is started by the WWW server program 911 via the CGI, the network device management program 921 acquires necessary MIB information on an agent of a network device to be managed, such as an agent 912 of a printer 902. In accordance with the acquired MIB information, the network device management program 921 produces WWW page data described in HTML and transfers the resultant data to the WWW server program 911. Herein, the printer 902 corresponds to the printer 102 shown in FIG. 1.
In the case of network management software using a WWW system, if an administrator of a network device (printer) forgets the device password assigned to the network device, the only possible manner of resetting a device password is to clear all current setting values by re-initializing the network device.
However, re-initialization of the network device causes all data set in the network device to be lost. This causes a significant loss to the user.